ALSA: opl3: small array underflow

There is a missing lower bound check on "pitchbend" so it means we can
read up to 6 elements before the start of the opl3_note_table[] array.

Thanks to Clemens Ladisch for his help with this patch.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/sound/drivers/opl3/opl3_midi.c b/sound/drivers/opl3/opl3_midi.c
index f62780ed64ad..7821b07415a7 100644
--- a/sound/drivers/opl3/opl3_midi.c
+++ b/sound/drivers/opl3/opl3_midi.c
@@ -105,6 +105,8 @@ static void snd_opl3_calc_pitch(unsigned char *fnum, unsigned char *blocknum,
                 int pitchbend = chan->midi_pitchbend;
                 int segment;
 
+                if (pitchbend < -0x2000)
+                        pitchbend = -0x2000;
                 if (pitchbend > 0x1FFF)
                         pitchbend = 0x1FFF;